The invention relates to an apparatus for cooling and finishing melt-spun filaments. In particular, the invention relates to a hollow quench stick tube that incorporates a spoiler skirt and a finish applicator that are spaced apart to form a spoiler void. The spaced arrangement of the spoiler skirt and finish applicator facilitates the creation of a partial vacuum in the spoiler void to draw a filament stream inwardly against the finish applicator such that the individual filaments are stabilized and sufficiently lubricated with a desired finishing agent. In another aspect, the invention is a method for cooling and finishing melt-spun filaments that incorporates the apparatus wherein the filament stream is drawn inwardly against the finish applicator.
The process in which a fiber-forming substance is melted and then extruded into air or other gas where the substance is cooled and solidified is known as melt spinning. Melt spinning is typically used for the manufacture of polyester and nylon. Various apparatus and methods exist for cooling and finishing melt-spun filaments. Existing apparatus incorporate spinnerets for extruding the filament, cooling tubes for lowering the temperature of the melt-spun filaments as they exit the spinneret, finish applicators for applying desired finishing agents, and filament guides for directing the filament stream towards the finish applicator and onto wind-up units for collecting the finished filament.
The finishing process, whereby finishing agents are applied to the cooled filaments, is a critical aspect of the melt-spinning process. Specifically, filaments are coated with a desired finishing agent, for example, a lubricating agent, to ensure that the structure of the filaments is not damaged during processing. Damaged filaments are not suitable for use in later processes. Existing apparatus address the problem of applying a sufficient amount of desired finishing agent to filaments. Specifically, known devices incorporate complex mechanisms for delivering the finishing agent and convergence devices for drawing individual filaments into a single thread. Unfortunately, these known devices are prone to mechanical failure (e.g., valve failure and clogging) and place additional, potentially damaging, strain on the individual filaments forming the filament stream.
For example, U.S. Pat. No. 5,886,055 to Schwarz discloses an apparatus and process for producing polyester multifilament yarn. Schwarz discloses a cooling tube for dispersing air against a filament stream, a downstream sealed tube connected to the cooling tube, a finish applicator connected to the lower end of the sealed tube, and a conical mantle that optionally encloses the sealed tube. As described, Schwarz relies on a convergence device to direct the filament stream against the finish applicator and to combine the individual filaments into one thread. Thus, Scwharz depends upon the convergence device to ensure that the individual filaments contact the finish applicator. Nevertheless, existing convergence devices fail to adequately control the lateral movement (i.e., oscillation) of upstream sections of the filament stream that are adjacent the finish applicator. In other words, known convergence devices affect the downstream sections of the filament stream, yet fail to prevent lateral movement of upstream sections of the filament stream, and specifically, upstream sections affected by air drawn downwardly by the filament stream (i.e., entrained air). Thus there exists a need for an apparatus and method that controls the lateral movement of the filament stream adjacent the finish applicator.
U.S. Pat. No. 6,174,474 B1 to Stein describes an apparatus and method for producing microfilament yarns with increased titer uniformity. Stein discloses a cone-shaped filament guide secured to a downstream section of a cooling tube that directs air against a filament stream to prevent contact between the filaments and filament guide. The cone-shaped filament guide accelerates entrained air and creates an air cushion that prevents filaments from contacting the filament guide and damaging the filament structure. Stein further discloses finish applicators that are separate from (i.e., not connected to) the cooling tube. Although the cone-shaped filament guide of Stein addresses the problem of preventing the oscillation of filaments at an upstream portion of the filament stream (i.e., prevent contact with the filament guide), it fails to address the problem of ensuring the application of sufficient finishing agent to the individual filaments. Rather, Stein positions the finish applicator below the cooling tube and incorporates the finish applicator as a convergence device. Unfortunately, the separation of the finish applicator from the cooling tube increases the amount of space required to operate the apparatus. Accordingly, there exists a need for a cooling and finishing apparatus in which the cooling tube and finish applicator are integrated and require less space during operation.
U.S. Pat. No. 4,988,270 to Stibal discloses an apparatus for cooling and conditioning melt-spun material. The Stibal devise includes a dispersing head, a multi-channel finish applicator, and a baffled opening at a downstream section of the dispersing head. Stibal relies upon a mechanically complicated valve seat, valve closure, and spike adjacent the upper end of the dispersing head to create an area of negative pressure to draw filaments into contact with the finish applicator. The valves and valve seats are prone to mechanical breakdown that results in downtime for maintenance periods. Thus, there exists a need for a mechanically reliable apparatus for cooling and finishing melt-spun filaments.
Existing methods for cooling and finishing filaments as disclosed in the above patents incorporate the devices described therein. Accordingly, there exists a need for a method of cooling and finishing filaments that control filament oscillation adjacent the finish applicator and that incorporates mechanically reliable apparatus.
It is therefore an object of the present invention to provide an apparatus and method for cooling and finishing melt-spun filaments that controls the lateral movement of the filament stream adjacent the finish applicator.
Yet another object of the invention is the provision of an apparatus and method for cooling and finishing melt-spun filaments that includes an integrated cooling tube and finish applicator to minimize the space required during operation.
A further object of the invention is the provision of an apparatus and method for cooling and finishing melt-spun filaments that is mechanically reliable and reduces the amount of downtime required for maintenance.
Still another object of the invention is the provision of a method of cooling and finishing melt-spun filaments that controls filament oscillation adjacent the finish applicator and that incorporates mechanically reliable apparatus.
The invention meets these objectives with an apparatus for cooling and finishing melt-spun filaments. In particular, the invention is a hollow quench stick tube, a finish applicator that substantially surrounds the hollow quench stick tube, and a spoiler skirt that substantially surrounds the hollow quench stick tube and that is spaced apart from the finish applicator to define a spoiler void. In another aspect, the invention is a method for cooling and finishing melt-spun filaments that incorporates the apparatus wherein a partial vacuum created in the spoiler void draws the filaments inwardly against the finish applicator.
The foregoing and other objects and advantages of the invention and the manner in which the same are accomplished will become clearer based on the following detailed description taken in conjunction with the accompanying drawings in which: